/Engine/Source/Runtime/OpenGLDrv/Public/OpenGLDrv.h
Retrieves the most recently resolved timing measurement. The unit is the same as forFPlatformTime::Cycles(). Returns 0 if there are no resolved measurements.
Value of the most recently resolved timing, or 0 if no measurements have been resolved by the GPU yet.
uint64 GetTiming ( bool bGetCurrentResultsAndBlock )